System and Method for Dynamically Swapping Master and Slave Phys to Allow Asymmetry in Energy Efficient Ethernet

1. A method, comprising: transmitting a control message from a first physical layer device operating in a master mode to a second physical layer device operating in a slave mode, said transmission being in response to a determination of a change in operating state of a first direction of transmission from said first physical layer device to said second physical layer device, wherein said change in operating state impacts an ability of said second physical layer device to recover a clock from a signal received from said first physical layer device; switching said first physical layer device from said master mode to said slave mode, wherein said slave mode is responsive to said second physical layer device that has switched from said slave mode to said master mode in response to said transmitted control message; and changing an operating state of said first direction of transmission, said change in operating state causing at least part of said first physical layer device to transition to a low power state.

2. The method of claim 1 , wherein said transmitting comprises transmitting an in-band control message.

3. The method of claim 1 , wherein said transmitting comprises transmitting an out-of-band control message.

4. The method of claim 1 , wherein said switching comprises activating a phase locked loop for use by said first physical layer device.

5. The method of claim 1 , wherein said changing comprises transitioning said first physical layer device into a subset physical layer device mode.

6. The method of claim 1 , wherein said changing comprises transitioning said first physical layer device into a low power idle mode.

7. A method, comprising: receiving a control message by said first physical layer device from said second physical layer device, said first physical layer device communicating with said second physical layer device while said first physical layer device is in a slave mode and said second physical layer device is in a master mode, said control message being generated in response to a determination of a change in operating state of a first direction of transmission from said second physical layer device to said first physical layer device relative to a change in operating state of a second direction of transmission from said first physical layer device to said second physical layer device, wherein said change in operating state impacts an ability of said first physical layer device to recover a clock from a signal received from said second physical layer device; switching, in response to said received control message, said first physical layer device from a slave mode to a master mode; and changing an operating state of said first direction of transmission, said change in operating state causing at least part of said first physical layer device to transition to a low power state.

8. The method of claim 7 , wherein said receiving comprises receiving an in-band control message.

9. The method of claim 7 , wherein said receiving comprises receiving an out-of-band control message.

10. The method of claim 7 , wherein said changing comprises transitioning said first physical layer device into a subset physical layer device mode.

11. The method of claim 7 , wherein said changing comprises transitioning said first physical layer device into a low power idle mode.

12. The method of claim 7 , wherein said master mode and slave mode is for a loop timing function.

13. A control method, comprising: determining whether an operating state of a first transmission direction between a first physical layer device and a second physical layer device is to be changed relative to a second direction of transmission opposite said first direction of transmission, wherein said change in operating state causes at least part of said first physical layer device to transition to a low power state, said transition impacting an ability of said second physical layer device to recover a clock from a signal received from said first physical layer device; and if it is determined that said operating state of said first direction of transmission is to be changed, then transmitting a control message from said first physical layer device to said second physical layer device, said control message requesting a reassignment of said second physical layer device from a slave physical layer device to a master physical layer device.

14. The method of claim 13 , wherein said transmitting comprises transmitting using physical layer communication.

15. The method of claim 13 , wherein said transmitting comprises transmitting using sequence ordered sets.